Electrostatic device for sound reproduction



llm -g E933., Q, KYLE gf ELEOTROSTATIO DEVICE FOR SOUND REPRODUCTION Filed Oct. 5. 1928 I OOOOOOOOOOOOOG Patented Mar. 24, 1931 NETE@ STATES PATENTY GFFICE COLIN KYLE, F GENEVA, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, T0 UNITED RIHRQDUCERS PATENTS CORPORATION, 0F ST. CHARLES, ILLINOIS, A. CORPORA- TION 0F NEVADA ELEGTROSTATIG DEVICE FR SOUND REPRODUCTION' l .Application med. October 5, 1.928. Serial No. 310,474.

The present invention relates to electrostatic devices for sound reproduction and production.

Among the objects of the invention is to provide a novel electro-static sound producer and reproducer having conductors' and dielectric having the properties or characteristics of permitting the rapid dissipation or discharge of static charges, especially those lo tending to residually remain or lag in the material of the dielectric. ln the illustrative embodiment, the dielectric may be of sheet material stretched over the surface of a metal plate having openings, and carrying on its opposite face a flexible metal member or coating, such as gold or silver leaf, aluminum foil and other like and similar conductors, or even a coating of metal suitably applied thereto'. The dielectric is one that has a slight amount of conductivity or one that is not a perfect insulator or dielectric, so that dissipation or draining oil' of static charges, particularly that tending to remain residually or to lag in the material of the dielectric, may be rapidly effected.

I have discovered that by using a dielec tric which is not perfect insulator but has a slight amount df conductivity or leakage, the static charges' change polarity or potential levels without lag. The slight amount of conductivity in the dielectric is not such as vto affect the charge in the main but offers an ecient way for the rapid discharge, draining olf or dissipation of the part of the charge that would normally tend to residually remain or lag in the dielectric material. As examples of such dielectric, are rubberized nainsoolr, rubberized silk, fabrics impregnated with insulating material, low grade rubber, gutta percha, vulcanized cloth, vulcanite, fabrics such as cotton, silk, linen and the like, resinized with resinous compounds, such as synthetic resins and other like and similar materials.

Other objects, capabilities, advantages and featuresare comprehended by the invention as will later appear and are inherently possessed thereby.

I lteferring to the drawings, Fig. l is a view in elevation of a sound producer or reproducer constructed in accordance with the invention, withparts shown broken away; and Fig. 2 is a fragmentary sectional view on an enlarged scale.

Referring morein detail to the drawings, the embodiment selected to illustrate the invention is shown with a base 1, carrying a frame 2 suitably supporting a plate 3 of metal and having avnumber of openings 4. The plate is preferably made with a number of depressions or troughs with inclined or deflected surface areas or regions between the main surface 5 of the plate and the openings 4, such surfaces diverging slightly from the plane of the surface as clearly shown in big. 2. Stretched to extend over the surface 5 of the plate is a dielectric l6 having th el characteristics above described. On the opposite side of the dielectric is provided a iexible metal surface or member 7 which may be foil or leaf of'metal or even a coating applied to the surface of the dielectric by spraying or the like.

The dielectrics may be of the materials above mentioned andhaving the characteristic-s described. In operation, the plate 3 and the flexible metal member 7 are connected to opposite sides of a circuit from which sound may be reproduced from electrical energy. Due to either opposite polarities of the charges or difference in potential levels of the charges on these metal members and as induced into the material or the surface of the dielectric 6, the dielectric will vibrate to produce sound. While I am not read to state what is the theory of the action or e ects of the static charges, it appears that the static charges are present upon the surface of the dielectric or in the material thereof, and

` to lag or to be slowl when the charges change 'either in polarity or potential levels, dissipationor discharge of the charges will in the main be effected rapidly, but under normal conditions, if the dielectric be a pure or absolute insulator, there is generally a residual charge that tends dissipated from the dielectric material. y use of the material herein disclosed, a slight amount of conductivity is present, which will ,efficiently permit the rapid leaking ofl' or drainage of the residual orlagging charges. In the case of using an impregnated fabric, it appears that the fibers or the threads of the fabric have suliicient conductivity characteristics to effect this result, yet not being such as to in an way materially effect the main charge. have found from experiments that the .changes in the charges are effected far more rapidly than has heretofore been possible with such dielectrics as high grade sheet rubber or the like, and that there is a clearer tone production effected. The noise usually parasitic upon the sound usually coming from a sound reproducer, is remarkably absent from this type of sound producer.

While I have herein described and uponl the drawings shown an illustrative embodiment of the invention, it isto be understood that the invention is not limited thereto but may comprehend other constructions, details, arrangements of parts and features without departing from the spirit thereof.

Having thus disclosed the invention, I claim:

1. Anelectro-static Ysound reproducer comprising conductors and an interposed dielectric having a slight amount of conductivity for therapid dissipation of static charges tending to remain residually in thel dielectric.

2. Anelectro-static sound reproducer comj prising conductors and an interposed insula tion ofj impregnated substance havimr a slight amount of conductivity for the rapida dissipation of static charges tending to remain residually in the* insulation.

3. An electro-static sound reproducer comprising conductors and an interposed dielectric having a resistivity slightly less than that of a perfect dielectric for rapidly discharging static charges tending to remain residually in the dielectric.

4. An electrostatic sound reproducer comprising a metal plate having openings therein, a flexible dielectric diaphragm juxtaposed to a face of the plate, and a flexible metallic member on the opposite surface of said diaphragm, said diaphragm having a resistivity slightly less than perfect resistivity whereby lag in static discharges may be reduced to a minimum.

5. An electro-static sound reproducer comprising a metal plate having openings therein, a flexible dielectric diaphragm stretched member on the opposite surface of said diaphragm, said diaphragm havin amount of conductivity for su stantially eliminating lag in static discharges.

6. An electrostatic translating device comv over a face of the plate, and a flexible metallic a Slight 

